Cutaneous basophil hypersensitivity is a delayed-in-time hypersensitivity reaction characterized by the infiltration of basophils at the site of antigen deposition. The present work is concerned with the mediators of transfer of cutaneous basophil hypersensitivity as released both from T lymphocytes and through the mediation of serum immunoglobulins. At present IgG1 is capable of transferring CBH and experiments are designed to determine if guinea pig IgE can also transfer CBH reactions. Studies on the specific receptor for IgG1, rabbit IgG, and guinea pig IgE are also being studied to determine the relationship, if any, between receptors on cells eliciting the passive cutaneous anaphylaxis reaction as opposed to those receptors concerned with cutaneous basophil hypersensitivity. The role of cutaneous basophil hypersensitivity in immune responses associated with variety of parasitic infections including schistosomiasis are being studied with specific reference to factors augmenting the afferent limb and mechanisms of effector action.